It is unlikely that any of the exposures are truly harmful for most babies, say the report's authors, and, based on current evidence, it is impossible to give an accurate assessment of risk.

Nevertheless, they say women should make an informed choice and at the same time "not wrap themselves up in a bubble".

'Empower not scare'

They say pregnant women can be exposed to a complex mixture of hundreds of chemicals at low levels through the food they eat and the everyday products they use.

Chemicals, such as bisphenol A and phthalates, can leach into food packaging and containers, including food and beverage cans and plastic-wrapped ready meals, say the authors, Dr Michelle Bellingham and Professor Richard Sharpe.

Among other warnings:

Cosmetic products and toiletries such as moisturisers, shower gel and sunscreen could, theoretically, also pose a chemical risk

Cleaning products, air fresheners and non-stick frying pans can be added to the hazard list

Pregnant women might also want to avoid decorating the new baby's room with fresh paint as breathing the fumes may be harmful

What risks?

Chemicals can enter your body through your skin or when you breathe, eat or drink

Your baby is exposed if the chemical passes from your blood, through the placenta

There is no consensus about which common household chemicals are harmful or whether they need to be avoided

Bisphenol A is found in drink and food cans, while phthalates are found in plastics, carpets, fabrics, cosmetics and new cars

Smoking and drinking too much alcohol can harm the baby

Experts agree that there are some foods - certain fish, for example - that you should avoid or cut down on when you're pregnant because they might make you ill or harm your baby

And do not assume natural or herbal products or remedies are safe, say the authors.

Prof Sharpe said: "For most environmental chemicals we do not know whether or not they really affect a baby's development, and obtaining definitive guidance will take many years.

"This paper outlines a practical approach that pregnant women can take, if they are concerned about this issue and wish to 'play safe' in order to minimise their baby's exposure."

He said women should not be alarmed and that the potential risks were likely to be small.

"We are trying to empower women, not scare them. There is a void at the moment in terms of information about chemicals," she said.

But many expert organisations were quick to criticise the RCOG advice.

Tracey Brown, of Sense About Science, said: "Pregnancy is a time when people spend a lot of time and money trying to work out which advice to follow, and which products to buy or avoid. The simple question parents want answered during pregnancy is: 'Should we be worried?'

"What we need is help in navigating these debates about chemicals and pregnancy. Disappointingly, the RCOG report has ducked this."

Rosemary Dodds, of the National Childbirth Trust, said it was unacceptable that pregnant women today were still having to make decisions without clear information on possible risks.

Janet Fyle, of the Royal College of Midwives, said pregnant women must take the advice with caution and use their common sense and judgement and not be unnecessarily alarmed about using personal care products, such as moisturisers, cosmetics and shower gels.

"There needs to be more scientific and evidence-based research into the issues and concerns raised by this paper," she said.

'No need to worry'

Dr John Harrison, director of Public Health England's Centre for Radiation, Chemical and Environmental Hazards, said: "We agree that it would be sensible for pregnant women to avoid using hazardous chemicals such as pesticides or fungicides as a precaution, or in line with product information. However, there is no evidence to suggest that chemicals in items such as personal care products are a risk to public health."

Dr Chris Flower of the Cosmetic, Toiletry and Perfumery Association said there was no need for anyone - pregnant or otherwise - to worry.

"The Royal College of Obstetricians and Gynaecologists has advised pregnant women to take a 'safety first' approach to cosmetic products and the good news is that there are already strict laws in place for cosmetics that allow us all to do just that."

He said a full safety assessment of every cosmetic product and all its ingredients was undertaken before a product could go on the market and, by law, all of the ingredients in a cosmetic product had to be listed on its packaging.